[Python-Dev] PEP 318 - posting draft (original) (raw)

Bob Ippolito bob at redivi.com
Wed Mar 24 11:55:54 EST 2004

On Mar 24, 2004, at 10:59 AM, Skip Montanaro wrote:

Bob> For example, ZopeX3 interfaces and PyProtocols interfaces both use Bob> sys.getframe() introspection to add a temporary metaclass so that Bob> they can ...

Guido> But the use cases are certainly very different than those for Guido> function/method decorators, and should be spelled out separately. Guido> For example, I'd like to see you show in much more detail how Guido> class decorators could be used to replace those Zope3 hacks. Bob, if you can come up with an example or two that won't consume infinite space, I'd be happy to add it/them to the Examples section of the PEP.

def provides(*interfaces): """ An actual, working, implementation of provides for the current implementation of PyProtocols. Not particularly important for the PEP text. """ def provides(typ): declareImplementation(typ, instancesProvide=interfaces) return typ return provides

class IBar(Interface): """Declare something about IBar here"""

class Foo(object) [provides(IBar)]: """Implement something here..."""

No stack introspection, no forced superclass or metaclasses, no side-effects on subclasses, etc. Foo is entirely unchanged by this operation (in PyProtocols at least).

-bob

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